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Keysight's new 34465A (6.5 digit) and 34470A (7.5 digit) bench multimeters

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Keyview:
Hi,

the data logging for the 34465A is puzzeling me.
Keysight specifies 5000 readings/s.
The user manual talks about 1000 readings/s in data logging mode.
I read that data logging mode allows zooming into data.

I would understand that reading rate is reduced from 5k/s to 1k/s when saving the data to an external file (e.g. via USB).
But, following the manual, it is  reduced to 1k/s when saving to internal memory, too.
Is this really the case?

Thank you for your feedback.

Btw, one of the prime reasons for my interest in the 34465A has not been
mentioned in this thread, yet: The guaranteed accuracy of this device for VAC in the low end down to 1 mV
is only outperformed by the high-end Agilent Keysight 3458A and Fluke 8508A as far as I can see.
Even the 34461A is hard to beat in the range 1-5 mV AC.  :-+

HighVoltage:

--- Quote from: Keyview on November 05, 2015, 10:38:50 pm ---the data logging for the 34465A is puzzeling me.
Keysight specifies 5000 readings/s.
The user manual talks about 1000 readings/s in data logging mode.

--- End quote ---

Welcome to the forum.
The 34465A and the 34470A both offer 5,000 rdgs/s in standard mode and 50,000 rdgs/s with the fast digitizer option
The 34461A only does 1,000 rdgs/s and has no option for faster readings

The storage memory on the 34465A and the 34470A 50,000 rdgs in standard mode and 2,000,000 rdgs with the memory option
The 34461A only does 10,000 rdgs and has no options for more memory




Keyview:

--- Quote from: HighVoltage on November 05, 2015, 11:36:30 pm ---Welcome to the forum.
The 34465A and the 34470A both offer 5,000 rdgs/s in standard mode and 50,000 rdgs/s with the fast digitizer option

--- End quote ---

Thank you for the welcome and your feedback.
Yes, that is why I was wondering about the maximum of 1,000 rdgs/s in the "data log mode" for the 34465A and 70A.
(source: user manual, pages 82 and 182, www.keysight.com/main/redirector.jspx?action=ref&cname=EDITORIAL&ckey=2345839&ml=eng)
Does the 5,000 rdgs/s for the 34465A apply only to "storing data" (page 99, above PDF) which does
not allow zooming into data? (The "digitize mode" on the other hand has 50,000 rdgs/s.)
Have a nice day!

Sparky:

--- Quote from: Sparky on July 20, 2015, 10:19:30 pm ---
--- Quote from: dadler on July 20, 2015, 07:23:02 pm ---
--- Quote from: HighVoltage on June 09, 2015, 08:59:52 pm ---And the fast DIG option also arrived and works really well.
I will post some test results of the DIG option soon.

--- End quote ---
Any updates on the DIG option?
It seems the DIG option is only really useful if you get the memory upgrade as well, 50k readings a second fills up fast when you have a 50k readings memory limit.

--- End quote ---
I'm also looking forward to hearing more about the DIG option...hopefully HighVoltagewill get a chance to write about it soon...

--- End quote ---

I was looking forward to someone posting about the DIG option and illustrating what 50k readings/sec is like of in terms of high enough sample rate and resolution to capture micro- and milli-amp magnitude currents (in battery powered embedded circuits, which is my application).  That never happened and in the meantime I bought the DIG + MEM options myself.  I'm posting some results to show what can be achieved for anyone else who might be curious about this.

Test Setup
Keysight 34465A with the DIG and MEM options; valid calibration.  Current range set to 1A, and digitize option used to acquire readings at maximum 50k readings/sec for 40 seconds (total 2M readings).  The readings were saved to USB 2.0 drive as CSV file and later plot in MATLAB.

Device Under Test
Custom Texas Instruments CC3200 (MCU + WiFi) board.  Current measured at output of Li-Ion battery before input to LDO regulator. 

I attached 4 .png files which are MATLAB plots of Current [mA] vs Time [sec].  The images are of the same data set "zoomed" in on the x- and y-axis to highlight successively finer details. 

Image 01 10 sec duration showing system starting up; lots of current spikes while connecting to WiFi.
Image 02 1 sec duration of system in "idle" state.  Possible to identify 3 different periodic tasks: 1) MCU wakes at 4Hz (~20mA "blocks"); 2) WiFi applications processor responding to maintenance-type packets from wireless router at 2 Hz (~350mA "spikes"); and 3) A sensor running asynchronously from MCU at ~8Hz (~250mA "spikes").
Image 03 0.1 sec duration zoom-in to the MCU wake; can see various levels of activity as the system comes out of sleep and then returns to sleep.
Image 04 0.01 sec duration zoom-in showing an unknown periodic (~1.56kHz) current waveform.  I really wonder what part of TI CC3200 MCU is causing this, and why it's not staying at the lowest current draw!

Overall I have found the DIG and MEM options extremely useful in validating correct power management and sleep functions.  The ability to "zoom in" at many levels and see finer details is really remarkable.  I did not really expect this when using the 1A range.  It has enabled me to identify various sources of current draw and implement software changes leading to lower average current draw.  It is a bit of a challenge -- at each stage that you identify and then eliminate the biggest current draw you can see, you can then target the next one! (It's a tale of diminishing returns, but you get the idea!) 

Would still love to hear from HighVoltage and anyone else who has used the DMM for these kinds of applications --- it's very interesting seeing exactly how your system is operating in terms of the current waveform!

Have fun!
Sparky

SharpEars:

--- Quote from: Dr. Frank on October 12, 2015, 07:03:58 pm ---
A new FW for the +3ppm failure will be released in the next days / weeks, it's currently undergoing their tests.

Frank

--- End quote ---

It is January 2016 now and it doesn't look like the firmware that fixes this has been released yet. Am I correct in my assessment that the 34465A units are still not functioning properly as you described using current firmware 2.09? I am holding off on my purchase until Keysight fixes this issue.

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